An existing game makes a player act within a virtual game space according to an operation of a user, such as an action game or a role-playing game.
In these types of game, various kinds of non-player character such as an enemy character appear and each character act according to various action patterns.
Especially, for example, as written in a patent literature 1 the action pattern changes according to the change in the amount for a predetermined parameter such as physical energy amount for a single character.